Tell me please where can I translate the word Custom.

It is osclass core.

I found, but everything is translated there. Why is the translation not displayed then?

And why the habituation language for the site translation is not fully displayed? In the files everything is translated and the site does not display the entire translation

Not sure, it is not theme function.
What are your expectations here?

And why the habituation language for the site translation is not fully displayed? In the files everything is translated and the site does not display the entire translation

Did you tried to translate the core.po file? a lot of declaration of custom are there!

not only tried - and translated everything! still does not translate

Why is the word translated and not translated? English only

Did you uploadet the .mo and .po files after translation with Poeditor ?!!

Of course

This tricky world should be located in breadcrumbs.

Of course you'll excuse me, but where can I find these rusks? and how can they be translated into 2 languages?

@Hunter
Look into core translation files.

All translated - the result is the same, the word Custom and Edit in the translation files were transferred, but nothing changed on the site. These words are in plug-ins Favorite Items and All in One SEO Plugin, as well as in core.po.
Who knows the answer? What's the problem?Why was it translated but these 2 words do not display my translation on the site?

@Hunter
These words are in breadcrumb functionality that belongs to osclass core.
Based on documentation plugin can modify these titles, but I tested that and it never worked.